Hydroforming dies are used to form a cross-sectional profile in tubular parts. Commonly, a tubular part is placed within a die cavity. The die cavity is then filled with a Hydroforming Water-Based Fluid (HWBF) and pressurized to expand the tubular part outward against the die into the desired cross-sectional profile.
High pressure pumps are typically used when HWBF pressures are required in a hydroforming process. The flow rate of fluid from the high pressure pump is limited by the capacity of the pump providing the fluid. Typical single stage hydraulic pumps cannot provide variable displacement at pressures commonly required for hydroforming processes. Single stage pumps are limited to adding fluid in only one stroke direction of the pump. Therefore, fluid flow from the high pressure pump is not constant.
To provide the required amount of fluid at the required pressure may take a significant period of time, slowing the manufacturing process. To provide larger amounts of the high pressure fluid, larger pumps can be used. However, as the size of the pump providing high pressure fluid is increased so does the cost of the pump.